Multiresidue analysis and evaluation of the matrix effect on 20 pesticides in Brazilian maize (Zea mays L.) flour.

Maize consists of a cereal widely used in the preparation of different food products. Brazil is one of the world's largest maize producers. Several types of pesticides have been applied in maize crop, which can lead to the contamination of the derived products. The present work aims at the validation of multiresidue method to analyze the matrix effect and level of pesticides in maize flour. Twenty residues were investigated in samples commercialized in the state of Ceará, Brazil. The method was satisfactorily validated, according to parameters recommended by European Union. About 55% of the pesticides had an intense negative matrix effect. Multiresidue analyzes showed the presence of traces of fenitrotion in 20% of maize flour samples. Detected levels were below maximum residue limits recommended for maize. The results indicate that maize products need continuous monitoring to ensure food security.

Aflatoxins in maize flour produced in Mozambique and its risk assessment.

This study investigated the occurrence of aflatoxins (B1, B2, G1, and G2) in maize flour produced in Mozambique and to assess the associated carcinogenic risk. At different opportunities, 30 samples of maize flour were collected in five flour processing factories. These were determined by high-performance liquid chromatography (HPLC) with fluorescence detection. AFB1 concentrations ranged from 0.25 to 0.33 µg kg-1. The levels of total aflatoxins ranged from 0.55 to 1.05 µg kg-1, with a mean of 0.89 µg kg-1, for which maximum limits (MLs) are 10 and 4 µg kg-1 for Mozambique and the European Union, respectively. The calculated Margin of Exposure (MOE) for men and women was 243 and 231, respectively, so several folds below the risk cut-off level, indicating that consumption of such maize flour poses a potential risk of hepatocarcinoma related to aflatoxin exposure due to high intake of this food, a staple diet in most African countries.

Occurrence and Risk Assessment of Fumonisin B1 and B2 Mycotoxins in Maize-Based Food Products in Hungary.

Fumonisins are toxic secondary metabolites produced mainly by Fusarium verticillioides and Fusarium proliferatum. Their toxicity was evaluated, and health-based guidance values established on the basis of both Joint FAO/WHO Expert Committee on Food Additives (JECFA) and European Food Safety Authority (EFSA) recommendations. This study presents the results of fumonisin analyses in different maize- and rice-based food products in Hungary and the potential health risk arising from their dietary intake. In total, 326 samples were measured in 2017 and 2018 to determine fumonisins B1 and B2 levels. Three-day dietary record data were collected from 4992 consumers, in 2009. For each food category, the average concentration values were multiplied by the relevant individual consumption data, and the results were compared to the reference values. With respect to the maximum limits, one maize flour, two maize grits, and two samples of other maize-based, snack-like products had total fumonisin content minimally exceeding the EU regulatory limit. The mean daily intake for all maize-product consumers was 0.045-0.120 µg/kg bw/day. The high intake (95 percentile) ranged between 0.182 and 0.396 µg/kg bw/day, well below the 1 µg/kg bw/day tolerable daily intake (TDI) established by EFSA. While the intake calculations resulted in comforting results, maize-based products may indeed be contaminated by fumonisins. Therefore, frequent monitoring of fumonisins' levels and evaluation of their intakes using the best available data are recommended.

Exposure assessment and risk characterization of aflatoxins intake through consumption of maize products in the adult populations of Serbia, Croatia and Greece.

The main objective of this research was to perform an exposure assessment of aflatoxins intake through consumption of maize products in Serbia, Croatia, and Greece. Food consumption survey of maize-based products has been performed during 2017 in the three countries with at least 1,000 interviewees per country covering their dietary habits and body weight. Values for the concentration of aflatoxins were extracted from available research published in the last ten years. Finally, a Monte Carlo analysis of 100,000 iterations was performed to estimate the intake of aflatoxins from consumption of maize-based products. Results revealed that the estimated average exposure of adults to aflatoxins, from maize consumption, in each of the three countries was between 0.44 ng kg-1 bw day-1 and 5.59 ng kg-1 bw day-1. Margin of exposure values for the mean exposure levels, in all three countries, were between 30 and 389. Estimations for hepatocellular carcinoma cases/year/105 individuals, depending on the HBsAg+ prevalence, were 0.075-0.098, 0.006-0.008 and 0.020-0.026 for Serbia, Croatia and Greece, respectively.

Effects of pH and Temperature on the Stability of Fumonisins in Maize Products.

This paper is a study of the stability of fumonisins in dough based on maize flour prepared in a phosphate buffer with a pH of 3.5, 5.5 or 7.5 and baked at a temperature within the range of 100-250 °C. Buffers with various pH values were tested, since it is well-known that pH may significantly influence interactions of fumonisins with other substances. A standard analytical procedure was used to determine the concentration of free fumonisins. Hydrolysis in an alkaline medium was then applied to reveal the hidden forms, while the total fumonisins concentations was determined in another measurement. The total concentration of fumonisins was statistically higher in pH = 3.5 and pH = 5.5 than the concentration of free fumonisins; no similar difference was found at pH = 7.5. The applied phosphate buffer pH 7.5 may enhance solubility of fumonisins, which would increase extraction efficiency of free analytes, thereby decreasing the difference between concentrations of total and free fumonisins. Hydrolysed B1 fumonisin (HFB1) and partially hydrolysed B1 fumonisin (isomers a and b: PHFB1a and PHFB1b, respectively) were the main investigated substances. For baking temperatures below 220 °C, fumonisins were slightly more stable for pH = 5.5 than for pH = 3.5 and pH = 7.5. In both of these latter cases, the concentration of partially hydrolysed fumonisins grew initially (up to 200 °C) with an increase in the baking temperature, and then dropped. Similar behaviour was observed for free HFB1, which may suggest the following fumonisin degradation mechanism: initially, the tricarballylic acid (TCA) groups are removed from the molecules, and next, the HFB1 molecules disintegrate.

Use of liquid chromatography-high-resolution mass spectrometry for isolation and characterization of hydrolyzed fumonisins and relevant analysis in maize-based products.

The synthesis of partially hydrolyzed fumonisins (PHFB1 and PHFB2) and hydrolyzed fumonisins (HFB1 and HFB2) by chemical hydrolysis of pure fumonisins (FB1 and FB2) is reported together with the isolation and characterization by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Two structural isomers of partially hydrolyzed forms of FB1 and FB2 were identified, namely PHFB(1a) and PHFB(1b) and PHFB(2a) and PHFB(2b). Reaction yields were 21% for PHFB1 (sum of the two isomers), 52% for HFB1, 31% for PHFB2 (sum of the two isomers) and 30% for HFB2. Purity of each isolated compound was >98%. An LC-HRMS method for the simultaneous determination of fumonisins and their partially and totally hydrolyzed derivatives was applied to 24 naturally contaminated samples of maize and maize-based products. The majority of samples (18 out of 24) were contaminated with fumonisins B1 and B2. Fumonisins co-occurred with both partially hydrolyzed and hydrolyzed fumonisins in four nixtamalized samples (three masa flours and one tortilla chips). Co-occurrence of fumonisins with partially hydrolyzed fumonisins was also recorded in one sample of maize kernels and four samples of maize-based products (i.e. maize meal, cous-cous, corn-cakes and cornflakes). Mycotoxins levels ranged from 60 to 5700 µg/kg for fumonisins (sum of FB1 and FB2), from 10 to 210 µg/kg for partially hydrolyzed fumonisins (sum of PHFB1 and PHFB2) and from 30 to 200 µg/kg for hydrolyzed fumonisins (sum of HFB1 and HFB2). This is the first report of the isolation of PHFB2 and the co-occurrence of FB1, FB2, PHFB1, PHFB2, HFB1 and HFB2 in maize products. Considering the growing use of nixtamalized and maize-based products, the monitoring of fumonisins and their partially and totally hydrolyzed forms in these products may represent an important contributing factor in evaluating the relevant human risk exposure.

Effect of baking on reduction of free and hidden fumonisins in gluten-free bread.

The aim of the present work was to assess the influence of the baking process on the fumonisin content in gluten-free bread. The dough was made using two methods: without sourdough and with sourdough. Fumonisins were determined using high-performance liquid chromatography with ion-trap mass spectrometry. This study showed that the bread baking process caused a statistically significant drop in the mean concentration of free fumonisins: the reduction levels were 30 and 32% for the direct and sourdough-based methods, respectively. The lower reduction after baking was observed for hidden fumonisins: 19 and 10%, respectively. The presence of some compounds (such as proteins or starch) capable of stabilizing fumonisins during the baking process might be responsible for the observed increase in the hidden-to-free ratio from an initial 0.72 in flour to 0.83 in bread made from sourdough and to 0.95 in sourdough-free bread.